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KJO Korean Journal of Orthodontics

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pISSN 2234-7518
eISSN 2005-372X
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    • Original Article l 2019-11-25

      Effect of archwire stiffness and friction on maxillary posterior segment displacement during anterior segment retraction: A three-dimensional finite element analysis

      Choon-Soo Park, Hyung-Seog Yu, Jung-Yul Cha, Sung-Seo Mo, and Kee-Joon Lee

      Abstract : ObjectiveSliding mechanics using orthodontic miniscrews is widely used to stabilize the anchorage during extraction space closure. However, previous studies have reported that both posterior segment displacement and anterior segment displacement are possible, depending on the mechanical properties of the archwire. The present study aimed to investigate the effect of archwire stiffness and friction change on the displacement pattern of the maxillary posterior segment during anterior segment retraction with orthodontic miniscrews in sliding mechanics.MethodsA three-dimensional finite element model was constructed. The retraction point was set at the archwire level between the lateral incisor and canine, and the orthodontic miniscrew was located at a height of 8 mm from the archwire between the second premolar and first molar. Archwire stiffness was simulated with rectangular stainless steel wires and a rigid body was used as a control. Various friction levels were set for the surface contact model. Displacement patterns for the posterior and anterior segments were compared between the conditions.ResultsBoth the anterior and posterior segments exhibited backward rotation, regardless of archwire stiffness or friction. Among the conditions tested in this study, the least undesirable rotation was found with low archwire stiffness and low friction.ConclusionsPosterior segment displacement may be unavoidable but reducing the stiffness and friction of the main archwire may minimize unwanted rotations during extraction space closure.

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    • Original Article l 2020-03-25

      Three-dimensional cone beam computed tomography analysis of temporomandibular joint response to the Twin-block functional appliance

      Yuan-yuan Jiang, Lian Sun, Hua Wang, Chun-yang Zhao, and Wei-Bing Zhang

      Abstract : ObjectiveTo propose a three-dimensional (3D) method for evaluating temporomandibular joint (TMJ) changes during Twin-block treatment.MethodsSeventeen patients with Class II division 1 malocclusion treated using Twin-block and nine untreated patients with a similar malocclusion were included in this research. We collected their cone beam computed tomography (CBCT) data from before and 8 months after treatment. Segmentations were constructed using ITK-SNAP. Condylar volume and superficial area were measured using 3D Slicer. The 3D landmarks were identified on CBCT images by using Dolphin software to assess the condylar positional relationship. 3D models of the mandible and glenoid fossa of the patients were constructed and registered via voxel-based superimposition using 3D Slicer. Thereafter, skeletal changes could be visualized using 3DMeshMetric in any direction of the superimposition on a color-coded map. All the superimpositions were measured using the same scale on the distance color-coded map, in which red color represents overgrowth and blue color represents resorption.ResultsSignificant differences were observed in condylar volume, superficial area, and condylar position in both groups after 8 months. Compared with the control group (CG), the Twin-block group exhibited more obvious condyle-fossa modifications and joint positional changes. Moreover, on the color-coded map, more obvious condyle-fossa modifications could be observed in the posterior and superior directions in the Twin-block group than in the CG.ConclusionsWe successfully established a 3D method for measuring and evaluating TMJ changes caused by Twin-block treatment. The treatment produced a larger condylar size and caused condylar positional changes.

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    • Original Article l 2019-11-25

      Three-dimensional analysis of tooth movement in Class II malocclusion treatment using arch wire with continuous tip-back bends and intermaxillary elastics

      Ji-Yea Lee, Sung-Kwon Choi, Tae-Hoon Kwon, Kyung-Hwa Kang and Sang-Cheol Kim

      Abstract : ObjectiveThe aim of this study was to analyze three-dimensional (3D) changes in maxillary dentition in Class II malocclusion treatment using arch wire with continuous tip-back bends or compensating curve, together with intermaxillary elastics by superimposing 3D virtual models.MethodsThe subjects were 20 patients (2 men and 18 women; mean age 20 years 7 months ± 3 years 9 months) with Class II malocclusion treated using 0.016 × 0.022-inch multiloop edgewise arch wire with continuous tip-back bends or titanium molybdenum alloy ideal arch wire with compensating curve, together with intermaxillary elastics. Linear and angular measurements were performed to investigate maxillary teeth displacement by superimposing pre- and post-treatment 3D virtual models using Rapidform 2006 and analyzing the results using paired t-tests.ResultsThere were posterior displacement of maxillary teeth (p < 0.01) with distal crown tipping of canine, second premolar and first molar (p < 0.05), expansion of maxillary arch (p < 0.05) with buccoversion of second premolar and first molar (p < 0.01), and distal-in rotation of first molar (p < 0.01). Reduced angular difference between anterior and posterior occlusal planes (p < 0.001), with extrusion of anterior teeth (p < 0.05) and intrusion of second premolar and first molar (p < 0.001) was observed.ConclusionsClass II treatment using an arch wire with continuous tip-back bends or a compensating curve, together with intermaxillary elastics, could retract and expand maxillary dentition, and reduce occlusal curvature. These results will help clinicians in understanding the mechanism of this Class II treatment.

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    • Original Article l 2020-11-25

      Innovative customized CAD/CAM nickel-titanium lingual retainer versus standard stainless-steel lingual retainer: A randomized controlled trial

      Emilie Gelin , Laurence Seidel, Annick Bruwier, Adelin Albert, Carole Charavet

      Abstract : Objective: To compare computer-aided design and computer-aided manufacturing (CAD/CAM) customized nitinol retainers with standard stainlesssteel fixed retainers over a 12-month study period. Methods: This randomized controlled trial (RCT) was conducted on 62 patients randomly allocated to a control group that received stainless-steel retainers or a test group that received customized CAD/CAM nickel-titanium retainers. Four time points were defined: retainer placement (T0) and 1-month (T1), 6-month (T2), and 12-month (T3) follow-up appointments. At each time point, Little’s irregularity index (LII) (primary endpoint) and dental stability measurements such as intercanine width were recorded in addition to assessment of periodontal parameters. Radiological measurements such as the incisor mandibular plane angle (IMPA) were recorded at T0 and T3. Failure events (wire integrity or debonding) were assessed at each time point. Results: From T0 to T3, LII and other dental measurements showed no significant differences between the two groups. The data for periodontal parameters remained stable over the study period, except for the gingival index, which was slightly, but significantly, higher in the test group at T3 (p = 0.039). The IMPA angle showed no intergroup difference. The two groups showed no significant difference in debonding events. Conclusions: This RCT conducted over a 12-month period demonstrated no significant difference between customized CAD/CAM nickel-titanium lingual retainers and standard stainlesssteel lingual retainers in terms of dental anterior stability and retainer survival. Both retainers eventually appeared to be equally effective in maintaining periodontal health.

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    • Original Article l 2019-05-25

      Influence of changing various parameters in miniscrew-assisted rapid palatal expansion: A three-dimensional finite element analysis

      Soungjun Yoon, Dong-Yul Lee, and Seok-Ki Jung

      Abstract : ObjectiveThis study aimed to analyze the effect of changing various parameters of the bone-borne rapid palatal expander (RPE) using the finite element method (FEM).MethodsIn eight experimental groups, we investigated the effect of the number, position, and length of miniscrews; positional changes of the expander; and changes in the hook length on maxillary expansion. In finite element analysis, we compared the magnitude and distribution of stress, and the displacement changes following expansion of the bone-borne RPE.ResultsWhen we compared the number and position of miniscrews, placing miniscrews in the anterior and posterior sides was advantageous for maxillary expansion in terms of stress distribution and displacement changes. Miniscrew length did not significantly affect stress distribution and displacement changes. Furthermore, anteroposterior displacement of the expander did not significantly affect transverse maxillary expansion but had various effects on vertical changes of the maxilla. The maxilla rotated clockwise when the miniscrews were placed in the anterior region. The hook length of the expander did not show consistent results in terms of changes in stress distribution and magnitude or in displacement changes.ConclusionsThe findings of this study suggest that changes in the location and length of the miniscrews and displacement of the bone-borne RPE could affect the pattern of the maxillary expansion, depending on the combination of these factors.

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    • Original Article l 2021-01-25

      Evaluation of mandibular buccal shelf characteristics in the Colombian population: A cone-beam computed tomography study

      Natalia Escobar-Correa , Maria Antonia Ramírez-Bustamante, Luis Alejandro Sánchez-Uribe, Juan Carlos Upegui-Zea, Patricia Vergara-Villarreal, Diana Milena Ramírez-Ossa

      Abstract : Objective: To evaluate the mandibular buccal shelf (MBS) in terms of the angulation and bone depth and thickness according to sex, age, and sagittal and vertical skeletal patterns in a Colombian population using cone-beam computed tomography (CBCT). Accordingly, the optimal site for miniscrew insertion in this area was determined. Methods: This descriptive, retrospective study included 64 hemi-arches of 34 patients. On CBCT images, the angulation, buccal bone depth (4 and 6 mm from the cementoenamel junction [CEJ] of MBS), and buccal bone thickness (6 and 11 mm from the CEJ of MBS) were measured at the mesial and distal roots of the mandibular first and second molars. Results: There were no statistically significant differences in the angulation, depth, and thickness of MBS between male and female patients. The values for the bone around the distal root of the mandibular second molar were significantly greater than the other values. The osseous characteristics were significantly better in participants aged 16–24 years. Class III patients exhibited the best osseous characteristics, with the bone depth at 6 mm being significantly different from that in Class I and Class II patients. Although values tended to be greater in patients with low angles, the difference was not statistically significant. Conclusions: MBS provides an optimal bone surface for miniscrew insertion, with better osseous characteristics at the distal root of the mandibular second molar, 4 mm from CEJ. Adolescent patients, Class III patients, and patients with a low angle exhibit the most favorable osseous characteristics in the MBS area.

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    • Case Report l 2019-05-25

      Total arch distalization with interproximal stripping in a patient with severe crowding

      Min-Ho Jung

      Abstract : When a patient shows severe crowding, premolar extraction should be considered to provide required available space for alignment. If the third molars have already erupted and demonstrate a poor prognosis, third molar extraction and distalization of the posterior dentition can be used instead of premolar extraction to obtain space. Interproximal stripping (IPS) may also be used to gain space in cases of crowding. This case report describes the treatment of a 25-year-old man with severe crowding and mild lip protrusion. Although the crowding in the lower arch was severe enough to require first premolar extraction, distalization of the entire lower dentition with orthodontic mini-implants, extraction of the lower third molars, and IPS could successfully resolve the crowding and lip protrusion.

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    • Original Article l 2020-01-25

      Accuracy and reliability of measurements performed using two different software programs on digital models generated using laser and computed tomography plaster model scanners

      Leonardo T. Camardella, Edwin M. Ongkosuwito, E. Willemijn Penning, Anne Marie Kuijpers-Jagtman, Oswaldo V. Vilella, and K. Hero Breuning

      Abstract : ObjectiveThe aim of this study was to compare the accuracy and reliability of measurements performed using two different software programs on digital models generated using two types of plaster model scanners (a laser scanner and a computed tomography [CT] scanner).MethodsThirty plaster models were scanned with a 3Shape laser scanner and with a Flash CT scanner. Two examiners performed measurements on plaster models by using digital calipers and on digital models by using Ortho Analyzer (3Shape) and Digimodel® (OrthoProof) software programs. Forty-two measurements, including tooth diameter, crown height, overjet, overbite, intercanine and intermolar distances, and sagittal relationship, were obtained.ResultsStatistically significant differences were not found between the plaster and digital model measurements (ANOVA); however, some discrepancies were clinically relevant. Plaster and digital model measurements made using the two scanning methods showed high intraclass coefficient correlation values and acceptable 95% limits of agreement in the Bland-Altman analysis. The software used did not influence the accuracy of measurements.ConclusionsDigital models generated from plaster casts by using laser and CT scanning and measured using two different software programs are accurate, and the measurements are reliable. Therefore, both fabrication methods and software could be used interchangeably.

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    • Original Article l 2020-11-25

      Part I. What drives Korean adults to seek orthodontic treatment: Reliability and validity of a measurement instrument for the perception of orthodontic treatment

      Min-Hee Oh , Eun-A Kim , Ae-Hyun Park, MinSoo Kim, Jin-Hyoung Cho

      Abstract : Objective: To develop a standardized instrument to measure the level of cognition for orthodontic treatment in adults, and verify its reliability and validity for assessing perceptions of orthodontic treatment in adults. Methods: A total of 406 adults aged 19–64 years were surveyed by an internet research system. A tool was developed through the instrument development and verification stages. The data were analyzed by correlation analysis, exploratory factor analysis, confirmatory factor analysis, and Cronbach’s α test. Results: The instrument consisted of 11 items covering four factors related to orthodontic treatment. Three items were related to general perception, four described the perception of the treatment for adults, two related to the treatment effects, and two related to the retention of orthodontic treatment. In the reliability test, Cronbach’s α was 0.845 for the 11 items. In assessments for individual components, Cronbach’s α was 0.764 for the general perception of orthodontic treatment, 0.705 for the perception of this treatment for adults, 0.707 for the effects of the treatment, and 0.701 for the retention of orthodontic treatment. Finally, a measurement instrument for the perception of orthodontic treatment in adults was designed to assess the 11 items on a four-point Likert scale. Conclusions: This study developed a standard measurement instrument for assessing the perception of orthodontic treatment in adults. The proposed instrument will enable additional studies on the influence of an adult’s perception of orthodontic treatment on the decision to undergo treatment.

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Journal Info.

January, 2021
Vol.51 No.1

Frequency: 6 times

Journal Impact Factor

  • 1.476
    2018 IF

  • 1.523
    5-Year IF

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Clinical Journal of Korean Association of Orthodontists